The present invention relates generally to electrical outlet boxes adapted to have electrical devices supported therein and attached to a cable extending through an opening in a wall of the outlet box, and more specifically to a cable locking device for locking the cable within the box.
Heretofore, cable connectors for supporting cables in components such as outlet boxes consisted primarily of a metal collar which had a peripheral thread and utilized a nut received on the thread to connect the collar into an outlet box. Subsequently a second clamping means usually grasped the cable and cooperated with the threaded collar to retain the cable within the outlet box. Not only is such an arrangment costly in terms of manufacturing several parts, there is a tremendous labor cost of inserting the various parts in appropriate sequence within the electrical box.
Another type of cable connector is a non-metallic bushing having a strain relief feature. These devices typically are inserted into the opening in the outlet box and incorporate a retaining means to prevent removal from the box. The cable is held in a position external from the box by the retaining means on the connector.
FIG. 1 of U.S. Pat. No. 3,701,505 shows a typical non-metallic bushing having a retaining means. The bushing is made to snap into the opening in the electrical outlet box and is retained in the opening by a number of spring like fingers. The retaining means for the electrical cable is external to the electrical outlet box and comprises a clamping mechanism which is operated by two screws.
FIGS. 9 & 10 of U.S. Pat. No. 3,493,205 show another example of a non-metallic bushing with a retaining means. This device uses a pawl means to engage the ratchet teeth of a plug member which traps the electrical cable. The bushing is snapped into the hole in the electrical outlet box.
U.S. Pat. Nos. 3,701,505 and 3,493,205 are in the opinion of applicant the closest prior art of which applicant is aware, but applicant does not represent that a search has been made or that no better art exists. A concise explanation of the relevance of each item has been given above and a copy of each item is being submitted with this specification. The relevance of the prior art indicated should not be given a limited interpretation. A cited prior art item may be found to have relevance in a passage other than the one referred to, or to have relevance in a sense different than as stated.